JP7809502B2 - Positioning system and positioning method - Google Patents

Description

The present invention relates to technology for measuring the position of underwater objects.

When the reference point for underwater work in port construction is on land or an existing structure, a known method is for divers and land-based surveyors to work together using an underwater staff to determine the new point for underwater work from the position of that reference point. However, while the underwater staff is sighted by the surveyor from land, as the water depth increases, it can be difficult for the diver to hold the underwater staff vertically due to factors such as tidal currents, which can result in large errors in the survey values. Furthermore, when the work area is several kilometers offshore, a known method is to calculate the new point using absolute coordinates from a land-based reference point determined using optical waves or GNSS, etc., and relative coordinates from an acoustic positioning device or other device on the sea. However, while acoustic positioning devices are installed on survey vessels and used to perform relative positioning, expensive detectors are required to accurately synchronize and correct the vessel's motion and position, and rigid metal fittings must be manufactured and installed on the survey vessel, etc., so if the vessel used for the survey is small, these fittings and devices can interfere with other work, and the vessel's motion cycle can become short, necessitating a more accurate attitude correction device.

For example, the underwater positioning system described in Patent Document 1 includes a pinger that is attached to an underwater object (object to be positioned) and emits an acoustic signal, and at least three hydrophones that can receive the acoustic signal from the pinger. The position of the object to be positioned is determined by calculating the difference in arrival time between the acoustic signals received by the different hydrophones.

Patent No. 968827

The present invention aims to provide a mechanism that allows for easy measurement of a desired position underwater.

In order to solve the above problem, the present invention provides a reference point acoustic wave transmitting device that transmits a reference point acoustic signal underwater, a position acoustic wave transmitting device that transmits a position acoustic signal underwater, and an acoustic wave receiving device that receives the reference point acoustic signal and the position acoustic signal underwater, wherein the reference point acoustic wave transmitting device comprises a first atomic clock and a reference point transmitting unit that is placed at a known position underwater and transmits a reference point acoustic signal at a predetermined reference point time based on the time measured by the first atomic clock, and the position acoustic wave transmitting device comprises a second atomic clock synchronized with the first atomic clock and a position transmitting unit that transmits a position acoustic signal underwater at a predetermined position reference time based on the time measured by the second atomic clock, and the acoustic wave receiving device comprises a third atomic clock synchronized with the first and second atomic clocks, a reference point receiving unit that receives the reference point acoustic signal transmitted from the reference point transmitting unit, and a position receiving unit that receives the position acoustic signal transmitted from the position transmitting unit and has a known positional relationship with the reference point receiving unit, and a first calculation unit that calculates the time from the reference point reference time at which the reference point transmitter transmitted a reference point acoustic signal to the time at which the reference point receiver receives the reference point acoustic signal transmitted from the reference point transmitter, based on the time measured by the third atomic clock, and calculates the position of the reference point receiver using this time and the known positions of each of the reference point transmitters; and a second calculation unit that calculates the time from the position reference time at which the position transmitter transmitted a position acoustic signal to the time at which the position receiver receives the position acoustic signal transmitted from the position transmitter, based on the time measured by the third atomic clock, and calculates the position of the position transmitter using this time and the positions of each of the position receivers calculated by the first calculation unit based on the positions of the reference point receivers, wherein the reference point receiver, the third atomic clock, the position receiver, the first calculation unit, and the second calculation unit are provided on a ship, and the reference point acoustic transmitting device is attached to a fixed object fixed underwater .

The location receiving units may be provided in at least three locations.

The reference point receiving unit and the position receiving unit may be the same receiving unit.

The reference point acoustic signal and the position acoustic signal may be transmitted simultaneously.

The acoustic receiving device may be attached to a vessel, underwater work vehicle, or a structure installed underwater.

In order to solve the above-mentioned problems, the present invention provides a positioning method performed by a reference point acoustic transmitting device that transmits a reference point acoustic signal underwater, a position acoustic transmitting device that transmits a position acoustic signal underwater, and an acoustic receiving device that receives the reference point acoustic signal and the position acoustic signal underwater, the method comprising the steps of: in the reference point acoustic transmitting device, a reference point transmitting unit arranged at a known position underwater transmits a reference point acoustic signal at a predetermined reference point reference time based on a time measured by a first atomic clock; in the acoustic receiving device, an underwater reference point receiving unit receives the reference point acoustic signal transmitted from the reference point transmitting unit; in the position acoustic transmitting device, an underwater position transmitting unit transmits a position acoustic signal at a predetermined position reference time based on a time measured by a second atomic clock synchronized with the first atomic clock; in the acoustic receiving device, an underwater position receiving unit receives the position acoustic signal transmitted from the position transmitting unit; The present invention provides a positioning method comprising the steps of: calculating, based on the time measured by a clock, the time from the reference point reference time at which the reference point transmitter transmitted a reference point acoustic signal to the time at which the reference point receiver receives the reference point acoustic signal transmitted from the reference point transmitter; and calculating the position of the reference point receiver using this time and the known positions of each of the reference point transmitters; and in the acoustic receiving device, a second calculation unit, based on the time measured by the third atomic clock, calculating the time from the position reference time at which the position transmitter transmitted a position acoustic signal to the time at which the position receiver receives the position acoustic signal transmitted from the position transmitter; and calculating the position of the position transmitter using this time and the positions of each of the position receivers calculated based on the calculated positions of the reference point receivers; wherein the reference point receiver, the third atomic clock, the position receiver, the first calculation unit, and the second calculation unit are provided on a ship, and the reference point acoustic transmitting device is attached to a fixed object fixed underwater .

The reference point acoustic transmitting device may include a step in which an unknown reference point transmitter, which is a reference point transmitter located at an unknown position underwater, transmits a reference point acoustic signal at a predetermined reference point reference time based on the time measured by a first atomic clock; a step in which an underwater reference point receiver in the acoustic receiving device receives the reference point acoustic signal transmitted from the unknown reference point transmitter; and a step in which a first calculation unit in the acoustic receiving device calculates the time from the reference point reference time at which the unknown reference point transmitter transmitted the reference point acoustic signal to the time at which the reference point receiver received the reference point acoustic signal transmitted from the unknown reference point transmitter based on the time measured by a third atomic clock synchronized with the first and second atomic clocks, and calculates the position of the unknown reference point transmitter using this time and the known positions of each of the reference point transmitters.

This invention makes it possible to easily measure a specific location in water at the desired timing.

1 is a device layout diagram showing an example of the overall configuration of a system according to an embodiment of the present invention. FIG. 1 is a block diagram showing an example of the configuration of a reference point acoustic wave transmitting device according to an embodiment. FIG. 1 is a block diagram showing an example of the configuration of a positional acoustic wave transmitting device according to an embodiment. FIG. 1 is a block diagram showing an example of the configuration of an acoustic wave receiving device according to an embodiment. 10 is a flowchart illustrating an example of an operation when positioning a reference point acoustic wave transmitting device in an embodiment. 10 is a table showing an example of a positioning result of a reference point acoustic transmitting device in the embodiment. 6 is a flowchart illustrating an example of an operation when positioning an acoustic wave transmitting device in an embodiment.

[Embodiment]
An example of an embodiment of the present invention will be described. FIG. 1 is an equipment layout diagram showing an example of the overall configuration of a positioning system according to an embodiment of the present invention. In FIG. 1, a dashed line S represents the water surface, and a solid line B represents the bottom of the water. The positioning system includes, for example, a computing device 2 provided on a ship 1 and at least three receiving units 3 installed underwater; a computing device 20, a GNSS (Global Navigation Satellite System) 30, and a transmitting unit 40 installed underwater, all of which are provided on a fixed object 10 such as an existing caisson; and a computing device 110 and a transmitting unit 120 provided on an underwater object 100. In the ship 1, the computing device 20 and the receiving units 3 are communicatively connected. In the fixed object 10, the computing device 20, the GNSS 30, and the transmitting unit 40 are communicatively connected. In addition, in the object 100, the computing device 110 and the transmitting unit 120 are communicatively connected. In Figure 1, the dashed line S representing the water surface and the solid line B representing the water bottom are represented as straight lines, so the fixed objects 10 appear to be lined up in a row, but in reality the fixed objects 10 do not have to be lined up in a row.

The GNSS 30, computing device 20, and transmitter 40 are installed in pairs at at least three locations. Each pair of GNSS 30, computing device 20, and transmitter 40 may be installed at three or more locations with different absolute coordinate values. The installation locations may be different on the same fixed object 10, or on different fixed objects 10. The height dimension of each fixed object 10 is such that its upper portion is always exposed above the water surface for the GNSS 30 to acquire absolute coordinate values and for synchronizing the atomic clock (described below). The computing device 20 and GNSS 30 are installed on this exposed portion above the water surface. The computing device 20 is a computer device that performs various calculations. The GNSS 30 receives satellite signals transmitted from multiple satellites orbiting the Earth to perform positioning. Methods of positioning include static positioning, RTK-GNSS, and network-type RTK-GNSS. The transmitter 40 is installed at a position on each fixed object 10 that is always below the water surface. The absolute coordinate position of the transmitter 40 can be determined by offset processing because the position of the GNSS 30 installed on the fixed object 10 and the distance from the position of the GNSS 30 to the position where the transmitter 40 is installed are known. The transmitter 40 installed on the fixed object 10 is placed at a known position in the water and functions as a reference point transmitter that transmits a predetermined acoustic signal (hereinafter referred to as the reference point acoustic signal) at a predetermined time (hereinafter referred to as the reference point reference time). The calculation device 20, GNSS 30, and transmitter 40 function as the reference point acoustic wave transmitting device of the present invention.

The object 100 is an underwater object to be positioned, such as an underwater backhoe, AUV (Autonomous Underwater Vehicle), underwater drone, ROV (Remotely Operated Vehicle), or underwater suspended load, or an underwater work machine performing some kind of work, materials associated with that work, or a diver working underwater. The object 100 may also be a structure installed underwater, such as a suspended block. The object 100 may also be a ship. The transmitter 120 provided on the object 100 functions as a position transmitter that transmits a predetermined acoustic signal (hereinafter referred to as a position acoustic signal) underwater at a predetermined time (hereinafter referred to as a position reference time). The computing device 110 and transmitter 120 function as the position acoustic wave transmitting device of the present invention.

At least three receivers 3 provided on the vessel 1 function as reference point receivers that receive reference point acoustic signals transmitted from transmitters 40 as reference point transmitters, and as position receivers that receive position acoustic signals transmitted from transmitters 120 as position transmitters. In other words, in this embodiment, the reference point receivers and position receivers are the same receiver (receiver 3). The calculation device 2 provided on the vessel 1 functions as a first calculation unit that calculates the position of each receiver 3 based on the reference point acoustic signals received by each receiver 3 as a reference point receiver. The calculation device 2 also functions as a second calculation unit that calculates the position of transmitter 120 as a position transmitter using the position acoustic signals received by each receiver 3 as a position receiver.

As described above, in this embodiment, the position of each reference point receiving unit (receiving unit 3) on the ship 1 is measured based on the reference point acoustic signal from each reference point transmitting unit (transmitting unit 40) whose position is known, the position of the ship 1 is identified from the position of the receiving unit 3, and the position of the object 100 is measured based on the position acoustic signal received by this receiving unit 3 (position receiving unit) from the transmitting unit 120 of the object 100. Here, each of these transmitting units 40, transmitting units 120, and receiving units 3 measures time based on atomic clocks that are synchronized with each other, so the measured position is highly accurate.

Figure 2 is a diagram showing the hardware configuration of the computing device 20. The computing device 20 is physically configured as a computer device including a processor 2001, memory 2002, storage 2003, communication device 2004, atomic clock (first atomic clock) 2005, and a bus connecting these components. Each of these devices operates on power supplied from a battery (not shown). Regarding power, shore power is used if available, and if not, small wind power generation, solar power generation, or a generator is used. Each function of the computing device 20 is realized by loading specific software (programs) into hardware such as the processor 2001 and memory 2002, allowing the processor 2001 to perform calculations, control communications via the communication device 2004, acquire data transmitted from other devices, and control at least one of reading and writing data from and to the memory 2002 and storage 2003.

The processor 2001, for example, runs an operating system to control the entire computer. The processor 2001 may be configured as a central processing unit (CPU) that includes an interface with peripheral devices, a control unit, an arithmetic unit, registers, etc.

Memory 2002 is a computer-readable recording medium and may be composed of, for example, at least one of ROM (Read Only Memory), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), RAM (Random Access Memory), etc. Memory 2002 may also be called a register, cache, main memory (primary storage device), etc. Memory 2002 can store executable programs (program code), software modules, etc. for implementing the method of this embodiment.

Storage 2003 is a computer-readable recording medium, and may be composed of at least one of, for example, an optical disk such as a CD-ROM (Compact Disc ROM), a hard disk drive, a solid-state drive, a flexible disk, a magneto-optical disk (e.g., a compact disk, a digital versatile disk, a Blu-ray (registered trademark) disk), a smart card, or flash memory (e.g., a card, a stick, or a key drive). Storage 2003 may also be referred to as an auxiliary storage device.

The communication device 2004 is hardware (transmission/reception device) for communication between computers, and communicates with the GNSS 30 and the transmitter 40 (reference point transmitter).

Figure 3 is a diagram showing the hardware configuration of the arithmetic device 110 in the object 100. The arithmetic device 110 is composed of a processor 1101, memory 1102, communication device 1103, and atomic clock 1104 (second atomic clock). The processor 1101, memory 1102, communication device 1103, and atomic clock 1104 (second atomic clock) share the same hardware as the processor 2001, memory 2002, communication device 2004, and atomic clock 2005 (first atomic clock) of the arithmetic device 20. The communication device 1103 communicates with the transmitter 120 (position transmitter). Each of these devices operates on power supplied from a battery (such as a storage battery) not shown.

Figure 4 is a diagram showing the hardware configuration of the calculation device 2 in the ship 1. The calculation device 2 is composed of a processor 201, memory 202, storage 203, communication device 204, and atomic clock 205 (third atomic clock). The processor 201, memory 202, storage 203, communication device 204, and atomic clock 205 (third atomic clock) share the same hardware as the processor 2001, memory 2002, communication device 2004, and atomic clock 2005 of the calculation device 20. The communication device 204 communicates with the receiving unit 3 (reference point receiving unit, position receiving unit). Each of these devices operates on power supplied from a battery (not shown) (such as a solar power generation unit).

In the above configuration, atomic clock 2005 (first atomic clock), atomic clock 1104 (second atomic clock), and atomic clock 205 (third atomic clock) are synchronized daily, thereby measuring synchronized times. For example, these atomic clocks synchronize at least once a day. It is desirable to synchronize these clocks in conjunction with synchronization between GNSS satellites. In the embodiments and variations described below, each atomic clock synchronizes in the air at least once a day.

Next, the operation of this embodiment will be described. Figure 5 is a flowchart showing an example of processing related to coordinate positioning of the installation position of the transmitter 40 (reference point transmitter). This processing is performed prior to positioning of the target object 100, which will be described later. In Figure 5, the calculation device 20 provided on each fixed object 10 determines the relative positional relationship between the installation position of the transmitter 40 and the installation position of the GNSS 30, causes the GNSS 30 to perform positioning processing, performs offset processing between the installation position of the transmitter 40 and the installation position of the GNSS 30, and measures the installation position of the transmitter 40 (step S11). Position information indicating the measured position, together with the ID of each transmitter 40, is transmitted to the calculation device 20 by, for example, the communication device 2004, and recorded.

Next, the calculation device 20 transmits the position information and ID of each transmitter 40 to the calculation device 2 of the acoustic receiving device via a reference point acoustic signal, and the position information and ID are stored by the calculation device 2 (step S12). As a result, the acoustic receiving device stores the position information of at least three transmitters 40 (reference point transmitters) along with the ID of each transmitter 40, as shown in FIG. 6. The transmitter ID is also the ID of the reference point acoustic transmitting device.

Next, Figure 7 is a flowchart showing an example of processing related to positioning of an object 100 (positional acoustic wave transmitting device). In Figure 7, when a predetermined reference point reference time arrives (step S101), each computing device 20 provided on each fixed object 10 instructs the transmitter 40 (reference point transmitter) to emit, for example, a pulsed acoustic signal based on the time measured by the atomic clock 2005 (first atomic clock). As a result, reference point acoustic signals are simultaneously emitted into the water from at least three or more transmitters 40 (step S102). At this time, each transmitter 40 emits an acoustic signal at, for example, a different frequency so that the transmitter 40 that is the source of each reference point acoustic signal can be identified.

Meanwhile, when a predetermined position reference time arrives based on the time measured by the atomic clock 1104 (second atomic clock) (step S103), the computing device 110 provided on the object 100 instructs the transmitter 120 (position transmitter) to emit, for example, a pulsed acoustic signal. This causes the transmitter 120 to emit a position acoustic signal into the water (step S104). At this time, acoustic signals of different frequencies are used so that the reference point acoustic signal and the position acoustic signal can be distinguished. Note that it is desirable that the reference point reference time and the position reference time, which are the times at which the reference point acoustic signal and the position acoustic signal are emitted, are the same time so that accurate positioning is possible even when the ship 1 and object 100 are moving.

Each receiving unit 3 provided on the vessel 1 receives the reference point acoustic signal transmitted from each transmitting unit 40 underwater, and also receives the position acoustic signal transmitted from the transmitting unit 120 .
Then, based on the time measured by the atomic clock 205 (third atomic clock), the calculation device 2 calculates the radio wave propagation time (time difference) from the predetermined reference point reference time described above to the time when each receiving unit 3 receives the reference point acoustic signal transmitted from each transmitting unit 40. Then, the calculation device 2 calculates the absolute position of each receiving unit 3 using the calculated time difference, the known positions of each transmitting unit 40 ( FIG. 6 ), and the speed of sound waves in water (step S105).

Because the distance between each transmitter 40 and each receiver 3 is different, the difference (time difference) between the reference point reference time at which the reference point acoustic signal is transmitted from each transmitter 40 and the reception time at which each receiver 3 receives the reference point acoustic signal is different. Therefore, the calculation device 2 can calculate the position (absolute position) of each receiver 3 from the relationship between the absolute coordinate positions of three or more transmitters 40, the time difference corresponding to each transmitter 40, and the speed of sound waves in water.

Next, the calculation device 2 calculates the radio wave propagation time (time difference) from the above-mentioned predetermined position reference time to the time when each receiving unit 3 receives the positional acoustic signal transmitted from the transmitting unit 120, based on the time measured by the atomic clock 205 (third atomic clock). The calculation device 2 calculates the absolute position of the transmitting unit 120 using the calculated time difference, the positions of each receiving unit 3 calculated in step S105, and the speed of sound waves in water (step S106). In other words, because the distances between the transmitting unit 120 and each receiving unit 3 are different, the difference (time difference) between the positional reference time when the positional acoustic signal was transmitted from the transmitting unit 120 and the reception time when each receiving unit 3 received each positional acoustic signal is different. Therefore, the calculation device 2 can calculate the position of the transmitter 120 (i.e., the position of the target object 100) from the relationship between the absolute coordinate positions of each of the three or more receivers 3, the time difference corresponding to each receiver 3, and the speed of sound waves in water, so it does not matter if the position acoustic signal from the transmitter 120 (position transmitter) is from a single location.

In the above-described embodiment, if the absolute coordinate position of each transmitter 40 is measured in advance, its position will be known thereafter, making it possible to calculate the underwater position of the object 100 at the desired timing on the vessel 1 using simple processing.

[Modification]
The above-described embodiment may be modified as follows: In addition, two or more of the following modifications may be combined and implemented.

It is desirable that the reference point receiving unit and the position receiving unit are the same receiving unit, but they do not necessarily have to be the same. If the relative positional relationship between the reference point receiving unit and the position receiving unit is known, it is possible to calculate the position of the position receiving unit from the position of the reference point receiving unit.

In addition, although this embodiment has been described using one object 100, if positional acoustic signals of different frequencies are used and the relationship between each acoustic signal and the object 100 is stored in advance by the computing device 2, the position of multiple objects 100 can be calculated.

Furthermore, in this embodiment, an example has been described in which the acoustic receiving device is attached to a ship, but this is not limiting, and the acoustic receiving device may also be attached to an underwater work machine or a structure installed underwater.

In the above-described embodiment, the explanation was based on the assumption that the position of the transmitter 40 (reference point transmitter) of each reference point acoustic transmitting device is known through positioning by GNSS or the like. Here, for example, when a new reference point acoustic transmitting device is installed, the position of the transmitter 40 (reference point transmitter) of that reference point acoustic transmitting device can also be determined as follows, rather than using GNSS or the like. In the newly installed reference point acoustic transmitting device, the transmitter 40 (reference point transmitter, hereinafter referred to as the unknown reference point transmitter) located at an unknown position underwater transmits a reference point acoustic signal at a predetermined reference point reference time based on the time measured by atomic clock 2005 (first atomic clock). Meanwhile, in the acoustic receiving device, the receiver 3 (reference point receiver) receives the reference point acoustic signal transmitted from the unknown reference point transmitter. Then, in the acoustic receiving device, the calculation unit 2 (first calculation unit) calculates the time from the reference point reference time at which the unknown reference point transmitter transmits a reference point acoustic signal to the time at which the receiver 3 (reference point receiver) receives the reference point acoustic signal from the unknown reference point transmitter, based on the time measured by the atomic clock 205 (third atomic clock). The position of the unknown reference point transmitter is calculated using this time and the known positions of each transmitter 40 (reference point transmitter) in the existing reference point acoustic transmitting device. This makes it possible to identify the position of a transmitter 40 (reference point transmitter) whose position is unknown in the reference point acoustic transmitting device. This position identification method can also be used to calibrate the position of a transmitter 40 (reference point transmitter) in an existing reference point acoustic transmitting device.

1: Ship, 2: Calculation unit, 3: Receiving unit, 10: Fixed object, 20: Calculation unit, 30: GNSS, 40: Receiving unit, 100: Object, 110: Calculation unit, 120: Transmitting unit.

Claims (7)

a reference point acoustic wave transmitting device that transmits a reference point acoustic signal underwater;
a positional acoustic wave transmitting device that transmits a positional acoustic signal underwater;
an acoustic wave receiving device that receives the reference point acoustic signal and the position acoustic signal underwater;
Equipped with
The reference point acoustic wave transmitting device is
a first atomic clock;
a reference point transmitter that is disposed at a known position underwater and that transmits a reference point acoustic signal at a predetermined reference point time based on the time measured by the first atomic clock;
Equipped with
The position acoustic wave transmitting device is
a second atomic clock synchronized with the first atomic clock;
a position transmitting unit that transmits a position acoustic signal underwater at a predetermined position reference time based on the time measured by the second atomic clock;
The acoustic wave receiving device is
a third atomic clock synchronized with the first atomic clock and the second atomic clock;
a reference point receiving unit that receives a reference point acoustic signal transmitted from the reference point transmitting unit;
a position receiving unit that receives the position acoustic signal transmitted from the position transmitting unit and has a known positional relationship with the reference point receiving unit;
a first calculation unit that calculates the time from the reference point reference time at which the reference point transmitter transmits the reference point acoustic signal to the time at which the reference point receiver receives the reference point acoustic signal based on the time measured by the third atomic clock, and calculates the position of the reference point receiver using the calculated time and the known positions of each of the reference point transmitters;
a second calculation unit that calculates, based on the time measured by the third atomic clock, a time from a position reference time at which the position transmitter transmits a positional acoustic signal to a time at which the position receiver receives the positional acoustic signal transmitted from the position transmitter, and calculates a position of the position transmitter using the calculated time and the positions of the position receivers calculated by the first calculation unit based on the positions of the reference point receivers;
the reference point receiving unit, the third atomic clock, the position receiving unit, the first calculation unit, and the second calculation unit are provided on one ship,
A positioning system characterized in that the reference point acoustic transmitting device is attached to a fixed object fixed in water. The positioning system according to claim 1 , wherein the position receiving units are provided in at least three locations. The positioning system according to claim 1 or 2, wherein the reference point receiving unit and the position receiving unit are the same receiving unit. 4. The positioning system according to claim 1, wherein the reference point acoustic signal and the position acoustic signal are transmitted simultaneously. 5. The positioning system according to claim 1, wherein the position acoustic wave transmitting device is attached to a ship, a diver, an underwater work machine, or a structure installed underwater. A positioning method performed by a reference point acoustic wave transmitting device that transmits a reference point acoustic signal underwater, a position acoustic wave transmitting device that transmits a position acoustic signal underwater, and an acoustic wave receiving device that receives the reference point acoustic signal and the position acoustic signal underwater,
In the reference point acoustic wave transmitting device, a reference point transmitter arranged at a known position in water transmits a reference point acoustic signal at a predetermined reference point time based on the time measured by a first atomic clock;
In the acoustic wave receiving device, an underwater reference point receiving unit receives the reference point acoustic signal transmitted from the reference point transmitting unit;
In the position acoustic wave transmitting device, an underwater position transmitting unit transmits a position acoustic signal at a predetermined position reference time based on a time measured by a second atomic clock synchronized with the first atomic clock;
In the acoustic wave receiving device, an underwater position receiving unit receives the position acoustic signal transmitted from the position transmitting unit;
In the acoustic wave receiving device, a first calculation unit calculates the time from the reference point reference time at which the reference point transmitter transmits a reference point acoustic signal to the time at which the reference point receiver receives the reference point acoustic signal based on the time measured by the first atomic clock and a third atomic clock synchronized with the second atomic clock, and calculates the position of the reference point receiver using the time and the known positions of each of the reference point transmitters;
a step in which, in the acoustic wave receiving device, a second calculation unit calculates, based on the time measured by the third atomic clock, a time from a position reference time at which the position transmitting unit transmits a position acoustic signal to a time at which the position receiving unit receives the position acoustic signal transmitted from the position transmitting unit, and calculates a position of the position transmitting unit using the time and the position of each of the position receiving units calculated based on the calculated positions of the reference point receiving units;
the reference point receiving unit, the third atomic clock, the position receiving unit, the first calculation unit, and the second calculation unit are provided on one ship,
A positioning method, characterized in that the reference point acoustic wave transmitting device is attached to a fixed object fixed in water. In the reference point acoustic wave transmitting device, an unknown reference point transmitter, which is a reference point transmitter arranged at an unknown position underwater, transmits a reference point acoustic signal at a predetermined reference point time based on the time measured by the first atomic clock;
In the acoustic wave receiving device, an underwater reference point receiving unit receives the reference point acoustic signal transmitted from the unknown reference point transmitting unit;
The positioning method according to claim 6, characterized in that in the acoustic receiving device, a first calculation unit calculates the time from the reference point reference time at which the unknown reference point transmitter transmits a reference point acoustic signal to the time at which the reference point receiver receives the reference point acoustic signal transmitted from the unknown reference point transmitter, based on the time measured by a third atomic clock synchronized with the first atomic clock and the second atomic clock, and calculates the position of the unknown reference point transmitter using this time and the known positions of each of the reference point transmitters.